So, I would think,
(b) P(X > 10) = [!not](everything up to and including 10) = 1-0.9994 = 0.0006
(d) P(6 ≤ X ≤ 11) :
X is between 6 and 11, AND it includes them both, so I choose one above 11, so 12 which is: 1.0000. Then I choose one below 6, so 5, so that I can include 6. Hence: 0.8042...